2012 BMW x6 Comfort Access all Four handle not working

[frank961106]

Greeting to all

I have a 2012 BMW x6, and my Comfort Access is not working. I wonder if I can find a solution to fix it other than going to the dealership and getting charged hundreds of dollars. so：
1. all four door handle is not working.
2. when I have the key inside the X6, I can start/stop the car without plugging the key into the keyhole.
3. i have switched many batteries for my key fob, and i can unlock the car with buttoms.

Therefore, I am thinking the comfort access module must have some problems. so can anyone tell me where is comfort access module is, and what might be the cause? or do i need to reprogram the key or something?

Thank you to whoever answered my post.
Frank